Mechanical fastening systems, of the type otherwise referred to as hook and loop fastener systems, have become increasingly widely used in various consumer and industrial applications. A few examples of such applications include disposable personal care absorbent articles, clothing, sporting goods equipment, and a wide variety of other miscellaneous articles. Typically, such hook and loop fastening systems are employed in situations where a refastenable connection between two or more materials or articles is desired. These mechanical fastening systems have in many cases replaced other conventional devices used for making such refastenable connections, such as buttons, buckles, zippers, and the like.
Mechanical fastening systems typically employ two components--a male (hook) component and a female (loop) component. The hook component usually includes a plurality of semi-rigid, hook-shaped elements anchored or connected to a base material. The loop component generally includes a resilient backing material from which a plurality of upstanding loops project. The hook-shaped elements of the hook component are designed to engage the loops of the loop material, thereby forming mechanical bonds between the hook and loop elements of the two components. These mechanical bonds function to prevent separation of the respective components during normal use. Such mechanical fastening systems are designed to avoid separation of the hook and loop components by application of a shear force or stress, which is applied in a plane parallel to or defined by the connected surfaces of the hook and loop components, as well as certain peel forces or stresses. However, application of a peeling force in a direction generally perpendicular or normal to the plane defined by the connected surfaces of the hook and loop components can cause separation of the hook elements from the loop elements, for example, by breaking the loop elements and thereby releasing the engaged hook elements, or by bending the resilient hook elements until the hook elements disengage the loop elements.
Mechanical fastening systems can be advantageously employed in disposable personal care absorbent articles, such as disposable diapers, disposable garments, disposable incontinence products, and the like. Such disposable products generally are single-use items which are discarded after a relatively short period of use--usually a period of hours--and are not intended to be washed and reused. As a result, it is desirable to avoid expensive components in the design of such products. Thus, to the extent that the hook and loop components are employed in such products, the hook and loop components need to be relatively inexpensive in terms of both the materials used and the manufacturing processes for making these components. On the other hand, the hook and loop components must have sufficient structural integrity and resiliency to withstand the forces applied thereto during normal wear of the absorbent article, in order to avoid potentially embarrassing situations for the wearer that can result from premature separation or disengagement of the hook and loop components.
U.S. Pat. No. 4,761,318 to Ott et al. discloses a loop fastening material useful in a mechanical fastening system for disposable articles. The loop fastening material disclosed by this patent includes a fibrous layer having a plurality of loops on a first surface adapted to be releasably engaged by a mating hook fastener portion and a layer of thermoplastic resin adhered to a second surface of the fibrous structure opposite the first surface. The thermoplastic resin anchors the loops in the fibrous structure.
U.S. Pat. No. 5,032,122 to Noel et al. discloses a loop fastening material useful in a mechanical fastening system for a disposable article. The loop fastening material disclosed by this patent includes a backing of orientable material and a multiplicity of fibrous elements extending from the backing. The fibrous elements are formed by continuous filaments positioned on and intermittently secured to the backing when the orientable material of the backing is in its dimensionally unstable state. The fibrous elements are formed by the shirring of the filaments between spaced, fixed regions of securement to the backing when the orientable material is caused to be transformed to its dimensionally stable state such that it is caused to contract or gather along its path of response. Thus, the loop material of this patent requires a backing of orientable material, such as an elastic or elastomeric or heat shrinkable material, that is caused to be transformed from a dimensionally stable state to a dimensionally unstable state and returned it to its dimensionally stable state.
U.S. Pat. No. 5,326,612 to Goulait discloses another a loop fastening material useful in a mechanical fastening system for a disposable article. The loop fastening material disclosed by this patent includes a nonwoven web secured to a backing. The nonwoven web serves to admit and entangle the hooks of a complementary hook component. The nonwoven web has a specified basis weight range of between about 5 to about 42 g/m.sup.2, an inter-fiber bond area of less than about 10 percent, and a total plan view bonded area of less than about 35 percent.
Notwithstanding the teachings of the aforementioned references, the need nonetheless exists for an improved loop fastening material for a mechanical fastening system, particularly as such are used in disposable personal care absorbent articles. The pattern-unbonded nonwoven loop fastening material of the present invention is soft and cloth-like and, therefore, aesthetically appealing in terms of appearance and feel. The pattern-unbonded nonwoven fabric of the present invention has sufficient structural integrity and dimensional stability that, unlike certain of the prior art loop materials, the need for attachment to a support or backing layer to anchor the fibers or filaments within the nonwoven fabric is eliminated. The pattern-unbonded nonwoven fabric of the present invention is relatively inexpensive to produce, especially in comparison to conventional loop materials formed by knitting, warp knitting, weaving, and the like, yet exhibits satisfactory, comparable and/or improved peel and shear strengths as compared to conventional loop fastening materials when used with commercially available hook fastener materials.